leetcode-852-Peak-Index-in-a-Mountain-Array

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描述

Let’s call an array A a mountain if the following properties hold:

  • A.length >= 3
  • There exists some 0 < i < A.length - 1 such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1]

Given an array that is definitely a mountain, return any i such that A[0] < A[1] < ... A[i-1] < A[i] > A[i+1] > ... > A[A.length - 1].

Example 1:

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Input: [0,1,0]
Output: 1

Example 2:

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Input: [0,2,1,0]
Output: 1

Note:

  1. 3 <= A.length <= 10000
  2. 0 <= A[i] <= 10^6
  3. A is a mountain, as defined above.

分析

唔，用二分查找的话，还能再优化一下。

解决方案2(Java)

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class Solution {
    public int peakIndexInMountainArray(int[] A) {
        int i = 0; 
        for (; A[i] <= A[i+1]; i++) {
        }
        return i;
    }
}

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